Usdot Tire Identification Number
You may notice another set of letters and numbers on your tire’s sidewall beginning with “DOT.” This is not an indication of tire size, but rather that the tire complies with Federal Motor Vehicle Safety Standards. The “DOT” stands for Department of Transportation and is followed by the tire identification number.
The first two letters or numbers after DOT refer to the manufacturing plant where the tire was produced and the last four numbers indicate the week and year the tire was made. The numbers 4318, for instance, indicate that the tire was manufactured during the 43rd week of 2018.
How To Find Your Tire Size
The saying “on size fits all” is not the case when it comes to tires. Each vehicle requires it’s own unique tire size to fit the frame of your car and to also make sure your tires can handle the weight or speed of the vehicle. Whether you’re looking into purchasing new tires or just want to know what tire size fits your car, it’s wicked easy to find out! Check out the two locations on your vehicle where your tire size is listed and also find out what those numbers actually mean below.
And Your Choice Of A Performance Car Is
In some cases, some cars lend themselves to extensive modification. For example, cars such as the Nissan Silvia in Japan, people fit larger staggered width wheels without any issues. The standard car comes on 16×6.5 wheels as standard, with a 205/55/16 size tyre all-round. One example had 17×8.5 Front wheels . Rear wheels were 17×9.5, so 1-inch diameter larger and 3 inches wider, with no modification to arches at all, no spacers needed!
Whether its a GT car, a Touring Car or a Tarmac Rally Car, its not often you will find a high-performance road car that doesnt feature bigger rims. Whether you have a high-performance car or not, keeping rolling radius similar makes sense if the car is used on the road a lot.
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How Do You Know What Size Wheels Fit On My Car
When determining the correct size of wheels for any vehicle, its essential to find what is called the proper fitment. There are several factors that go into finding the right fitment for every wheel and vehicle.
Those factors ensure the ability to mount the wheel as well as proper clearance in relation to the suspension. They include bolt patterns, offset, and of course, the size and type of wheel.
What Size Wheels Fit On My Car
Everyone has preferences when it comes to their vehicles. From the look to the performance, everyone wants something different out of their car or truck.
One of those common preferences is the size of the tires, and more specifically, the size of the wheels on which the tires would be installed. It has long been popular among car and truck enthusiasts to experiment with the size of their wheels. Not only does that change the look of the vehicle which is what many drivers who opt for the change are going for but changing the size of the wheel can also make a difference in the style and the feel of the drive.
Lets dive into the specifics of how the pros determine which wheels fit on which vehicles and, since its often done by amateur car enthusiasts, what issues might arise if done incorrectly.
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Alloy Wheel Fitting Guidance Here Is A Common Example Of An Alloy Wheel Offset Difference
Let us kick this off with what is a typical difference in offset on the same model of a wheel. In the image below, the wheel on the left is an ET35 wheel and the wheel on the right is an ET45 wheel. This is a 10mm Offset difference. The wheel on the left with the lower Offset is actually the one that will stick out the arches more as the wheel bolts to the hub 10mm further outwards than the 45mm one:
Can I Put Larger Tires On My Car
While it’s certainly possible to upgrade your tires’ size, it’s usually best to stick to your manufacturer-recommended tire size for optimal performance. Increasing the size of your tires may give your car more ground clearance, but it may also affect handling, drivetrain performance and fuel economy. Keep in mind the changes to key figures mentioned above, such as load index and speed rating, and how they may affect your vehicle’s capabilities if you decide to increase tire size.
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So How Much Bigger Alloy Wheels Can I Fit How Much Smaller Alloy Wheels Can I Fit
When fitting new wheels, more often than not, theyll usually be a different size. Here you can check below for potential alloy wheel or tyre fouling on suspension or arches/fenders.
The Alloy Wheel Fitment Guide tool below will let you see how much larger or smaller you can go without causing problems. Different size wheels can affect speedo reading, as well as overall gearing, so check your rolling radius below using the calculator.
Find your ideal tyre size using the Tyre and Alloy Wheel Fitment Guide calculator below to keep rolling radius similar. You could also use it to lower or raise the gearing of the car depending on what you want from the car. As mentioned before, lower gearing for faster acceleration, or higher gearing for fuel economy or more relaxed motorway journeys. Take note your speedo may need recalibrating if it becomes very inaccurate.
How To Identify A Compatible Tire Size
Changing one size up in tire width and one size down in aspect ratio will maintain approximate tire size. As an example, a P195/60R15 has an overall diameter of 24.2 inches and a load capacity of 87. Move up to a wider tire with a lower aspect ratio, P205/55R15, and the overall diameter is similar, at 23.9 inches, and the tire has the same load index of 87. In reading the tire sidewall, the aspect ratio is expressed in the center number, 60 and 55, respectively.
Online tire size calculators can be helpful when choosing alternate tire and wheel sizes.
Some tire size calculators give the size tire available for a specific make and model car. Consumer Reports tire selector tool can do that, plus it lists other sizes that are available for that car model and highlights compatible tested tires.
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What Is Wheel Width
Imagine a wheel separated from the vehicle and positioned upright as normal . As you look down at the wheel, the width is the measurement from left to right between the wheel edges, also called the wheel lips.
Wheel width is measured in inches, and typically in ½” increments.
Sometimes the four stock wheels and tires on a vehicle are the same width. This is called a square setup. A staggered setup is a case in which the wheel and tire widths at the front and rear axles are different. For more information see Staggered vs. square tire and wheel setups.
How To Find The Tyre Size For My Car
So youre now wondering how to find the right tyre size for your particular car. With the variety of tyre sizes available, its really important that youre putting the right size tyres for your individual car or van. One way to find which tyres would be correct for you would be to look at the sticker thats usually found on the inside of the driver side door jamb this is the same sticker that you can find tyre pressure on.
One method that many people use is to simply look at the current tyres on their car – the tyre markings tell you what size the tyre is. However, if youve recently bought the car second hand, then theres no guarantee that the previous owner has fitted the correct tyres.
Another way to find your tyre size is to consult your service or owners manual. So make sure you dont lose it!
Perhaps the easiest way to find the right tyre size for your car is to use our Tyre Size by Registration Plate tool. All you need to do is put in your number plate and the most likely fitment will show. We recommend you check this against your user manual to be extra sure, but we find that the tool is most often correct.
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Dont Break Your Brakes
Often though, the biggest problem going with smaller rims is the clearance of the brake calipers. On some cars fitted with upgraded brakes, you might be unable to fit certain wheels. Alloys with a dish or large lip can be worst, as the spokes tend to go further inwards. Spokes can catch on the caliper, making it impossible to spin the wheel. We wouldnt recommend fitting smaller brakes obviously, why would you? For safety reasons, it is better to upgrade your brakes than downgrade them!
What Wheel Offset Should I Use
Compared to specifications such as wheel diameter, wheel width and even stud patterns, the world of wheel offsets is an art in itself. In some cases, its fairly straightforward, say if you are just changing wheels to a similar size or even just a Plus one . However in other cases, if the vehicle is going beyond that for style, racetrack, or if you want that static look then if you want your vehicle rim fitment on point, you need to get the offset right. In this alloy wheel fitment guide, we will help you get it right.
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What Measurements Do You Need To Order Custom Wheels
This is an example of the dimensions you’ll need when ordering a custom three-piece wheel. As Forgeline’s David Schardt explained, “Our widths and offsets are virtually unlimited. With our combinations of rim halves available, we can build to an exact specification every time. Two-piece wheels are regulated by the sizes of barrels available and where the center can be welded in the rim. This limits offsets and backspaces.”
How Much Rubber Do You Need
One of the reasons why people opt for larger wheels and tires revolves around the contact patchspecifically, how much tire touches the ground at any given time. Maybe youve upgraded your engine for more power and now your tires break loose if you just look at them funny. Youre going to need more contact with the ground in order to use that extra power for more than sick burnouts.
There are two ways to increase the size of the tire’s contact patch: make it longer or wider. A longer patch of tire tread means that the tire’s overall diameter increases. This works better on a four-wheel-drive truck, but if you increase the diameter of the tire on most passenger cars, youll have problems.
First, theres the obvious issue. The tire can rub other parts of the car, like the wheel well.
Secondly, because the radius of the overall tire is larger, the cars effective gearing gets taller, which robs it of acceleration. Gear ratios are usually written like 4.10:1. The higher the first number is, the more that gear multiplies the input torque that ultimately spins your wheels. Problem is, it takes longer for a larger diameter tire to complete one rotation.
Parsing the Sidewall: What Those Numbers on the Side of Your Tire Mean
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What Is Wheel Offset
So far weve touched on exterior wheel measurements and clearance factors, but thats only part of the equation. What occurs in the space inside of your wheel barrels once theyre mounted is equally important.
Wheel offset is a measurement from the rear the wheel mounting face to the center of the wheel. Wheel offset adjusts the wheel either inward or outward once mounted. Similar to the diameter and width, offset directly affects vehicle component clearance.
Will Bigger Wheels Affect Handling
Typically, yes. Not only are bigger wheels often heavier and less maneuverable, but in the context of off-roading, a bigger, squishier tire will often have more sidewall than normal. Thus, the tire will be prone to more flex than stock, leading to lower on-road performance. Remember, Jamarrs looking for a somewhat off-road-ish tire, so the compromise might be worth it here.
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How Do You Measure Alloy Wheel Offset
Offset is the distance in millimetres from the centre line of the wheel to the wheels mounting face. As in the diagram below, the mounting face can be behind , in front of , or exactly in line with the centre. Red representing a Negative Offset, and Green a Positive Offset:
As the diagram above, alloy wheel offsets can be:
Where Can I Find More On What Wheels Will Fit My Car
The tire calculator is a great way to see the difference between your current wheel and tire setup, and the size youre desiring. Itll also show you recommended sizes that should be compatible with your vehicle.
As far as max size, thats a little harder. It will take a lot of Google fu to find that answer. For most mainstream cars, its usually a forum or Quora question thats likely already been answered years ago. For other less-common cars, finding your vehicles max size will likely be a series of trial-and-error. Bummer.
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Car Tires That Are Over 10 Years Old:
Any tire that is more than 10 years old is too thin to guarantee safe driving. At this stage, it is a must to replace it.
If you want to extend the lifespan of your tires, you can do the following:
- Check if your tires pressure surges every 2,000 to 3,000 miles. This will not directly improve your cars life but will most probably help in fuel efficiency, vehicle handling, and acceleration.
- Replace your tires every 5,000 7,500 miles to encourage uniform treadwear
- Get your tire configuration checked, as stated in your cars owners guide, or if you start to sense the car yank to a side while driving
- Check your tires frequently for any highway wreckages or impairments
- Examine your tires for any abnormalities in its treadwear because these can show glitches with your cars orientation or inflation.
- Be certain not to beat a tires extreme weight volume because this puts extreme compression on your tires
How Is A Two
Two-piece wheels consist of a barrel and an inner hub. The center fits into the barrel very tightly. So tight that the barrel is heated on a rotating platter until the aluminum expands enough for the center to slide inside. This wheel is being made at American Racing’s facility in California.
Backspace is determined by steel pucks that are stacked up under the center. These pucks limit how far down the center will slide down into the barrel. Once the barrel cools, it contracts and locks the center in place.
Of course, that interference fit isn’t enough to hold it all together under load, so a rotary welding machine stiches the two parts together. Two-piece wheel are less expensive than three-piece, but they are also more limited in backspacing and fitment options. Also, once welded together, they are nearly impossible to change. They can be a great option if they offer the backspacing and sizes you need.
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Uniform Tire Quality Grading
Another group of stamping on certain types of tires is the Uniform Tire Quality Grading or UTQG. This grading and stamping is required for passenger car tires in the all season and summer categories. Dedicated winter tires, Light Truck and Motorcycle tires are excluded from this requirement.
Quality grading is designed to make the tire purchase decision easier for you. Ideally, the system is intended to provide simple, comparative data so you can make an intelligent buying decision. However, the ratings are based upon test results achieved under special conditions. This means its possible to misinterpret the comparative data as it relates to your individual driving habits, conditions, etc. You should still rely on your service or tire professional for assistance.
Quality grading designates the comparative performance levels of a tire based on government-specified tests but commissioned by the individual tire manufacturers. All tire manufacturers are required to grade regular and all-season passenger tires in three categories:
Traction Grades AA, A, B and C The traction grades from highest to lowest are AA , A, B and C. They represent how well tires stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. C-rated tires will have the lowest traction performance.
WARNING: THE TRACTION GRADE ASSIGNED IS BASED ON A WET BRAKING TRACTION TEST AND DOES NOT INCLUDE CORNERING TRACTION.
So What Alloy Wheels Will Fit My Car
Well, after reading this guide, you have decided on getting some new rims, right? Just remember that if youre putting physically wider wheels on than before, you may need to change the offset in order for them to fit the way you want.
If, despite reading this alloy wheel fitment guide, you still have any questions regarding fitting, you can contact us and we will be happy to help!
You can also check out useful information on tyres including both Load Index and Speed Ratings in our separate tyre guide.
Wheel fitment widgets courtesy of wheel-size.com.
Due to the specific nature of the products we sell correspondence is preferred via email for accuracy of vehicle fitment.
Staff are available to help you seven days a week.
- Monday Friday:9am to 7pm
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